With a chance to match a season-best five-game win streak, the Rockets (43-34) gave up their most points in a regulation game this season on Saturday, losing 132-114 at Denver. Thirty-two of those points came off Houston's 19 turnovers.
Parsons, the team's second-highest scorer (15.3 ppg) behind James Harden (25.8), missed his second straight game with a right calf injury, while Delfino sat for a third in a row with flu-like symptoms.
"I think throwing the ball to them was a bigger focal point (than missing Chandler and Delfino)," said coach Kevin McHale after the 2-1 trip. "They had 32 points off our turnovers and 18 points off offensive rebounds. There's no defense for throwing them the ball for a layup. It's hard to overcome."
The Rockets, one game behind Golden State for the sixth spot in the West, will try to regroup at Toyota Center, where they've won 13 of 16. Had Utah (41-37) lost to the Warriors on Sunday, Houston could have locked up its first playoff berth since 2008-09 on Tuesday with a win. The Jazz, though, defeated Golden State 97-90 to move one-half game ahead of the ninth-place Los Angeles Lakers (40-37).
While the Rockets try to secure their postseason spot, the Suns (23-54) are finishing one of the worst seasons in team history. Phoenix -- last in the Western Conference -- kicks off its three-game trip after dropping a franchise-record seventh straight in the desert on Sunday, 95-92 to New Orleans.
The Suns' nine-game losing streak is their longest since a franchise-worst 13-game skid to begin 1996-97.
"There's no reason why to be positive," former Rocket Luis Scola said. "So how are we going to stay positive? Nobody should be positive. We have to work hard. The way we do it is we realize that we have problems and that we need to fix them."
The third quarter needs immediate attention. The Suns have been outscored by an average of 17.3 points in that period over the last three games.
"We have to look deeper into it and see what's going on because it's like a trend for us," said interim coach Lindsey Hunter, whose team has dropped 15 of 17.
The Suns came out flat in the second half of a 111-81 loss at Houston on March 13, getting outscored 32-17 in the 12 minutes after the break.
Houston ended a three-game skid in this series with the victory and ruined the return of Scola and point guard Goran Dragic, who re-signed with the Suns last summer after spending 2011-12 and a part of the previous season with the Rockets.
Dragic had 11 points and four assists in that contest, but he also scored 14 of his 18 in the fourth quarter of a 107-105 home win over Houston on March 9.
Harden, who set a team single-season record with his 631st free throw on Saturday, is 15 of 16 from the line against the Suns this season. He also has a team-best 56 points and 10 3-pointers in 15 attempts in the two games.
These teams play again Monday in the Suns' home finale.